Modify the WordPress theme

It is a method of modifying the file that is backed up (represented by a child theme) without touching the original when modifying the WordPress theme.

1. To easily check the children theme used, create a new folder in the “WP-Content/Theme” folder (for example, if the original theme is “TwentyfiftEen”, create a folder with “TwentyfiftEen-Child”)
2. Copy the “Style.css” of the original theme to the child theme folder and modify “Theme Name” and “Themplate” as follows.

   /*
   Theme Name: Twenty Fifteen Child
   Theme URI: https://wordpress.org/themes/twentyfifteen/
   Template: twentyfifteen
   Author: the WordPress team
   Author URI: https://wordpress.org/
   Description: Our 2015 default theme is clean, blog-focused, and designed for clarity. Twenty Fifteen's simple, straightforward typography is readable on a wide variety of screen sizes, and suitable for multiple languages. We designed it using a mobile-first approach, meaning your content takes center-stage, regardless of whether your visitors arrive by smartphone, tablet, laptop, or desktop computer.
   Version: 1.5
   License: GNU General Public License v2 or later
   License URI: http://www.gnu.org/licenses/gpl-2.0.html
   Tags: black, blue, gray, pink, purple, white, yellow, dark, light, two-columns, left-sidebar, fixed-layout, responsive-layout, accessibility-ready, custom-background, custom-colors, custom-header, custom-menu, editor-style, featured-images, microformats, post-formats, rtl-language-support, sticky-post, threaded-comments, translation-ready
   Text Domain: twentyfifteenTemplate: twntyfifteen
   This theme, like WordPress, is licensed under the GPL.
   Use it to make something cool, have fun, and share what you've learned with others.
   */
   

3. Create “Functions.php” as the source below in the child theme folder.

   <?php
   add_action( 'wp_enqueue_scripts', 'theme_enqueue_styles' );
   function theme_enqueue_styles() {
   wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
   }
   ?>
   

4. Copy the “Screenshot.png” of the original theme to the child theme folder.
5. You can copy the file of the original theme to be modified to the child theme folder and modify it.

(Note: http://codex.wordpress.org/child_themes)